CN1341576A

CN1341576A - Preparation of high-purity titanium biboride ceramic micropowder by using self-spreading high-temp. reduction synthesis process

Info

Publication number: CN1341576A
Application number: CN 01128497
Authority: CN
Inventors: 傅正义; 王为民; 王皓
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Science and Engineering WUSE; Wuhan University of Technology WUT
Priority date: 2001-09-27
Filing date: 2001-09-27
Publication date: 2002-03-27

Abstract

The preparation method of high-purity TiB2 ceramic micropowder uses active metal reducing agent and cleap oxide raw material, and adopts the following steps: uniformly mixing TiO2, B2O3 and metal Mg powder, die-pressing and forming, placing the above-mentioned obtained material in a self-spreading high-temp. synthesis equipment with argon protection at normal temp. and normal pressure, lighting to make combustion, breaking combustion product, pickling so as to obtain the invented high-purity TiB2 ceramic micropowder. As compared with traditional carbon thermal reduced TiB2 ceramic powder said invention possesses the advantages of high purity, fine crystal grain, simple process and low energy consumption and time consumption, and as compared with SHS simple substance synthetic TiB2 ceramic powder it is low in production cost.

Description

Preparation of high-purity titanium diboride ceramic micropowder by self-propagating high-temperature reduction synthesis method

Technical Field

The invention relates to a refractory compoundand a solid-phase synthesis method thereof.

Background

Titanium diboride ceramic powder is an important novel engineering ceramic raw material, and important physical and chemical properties of the titanium diboride ceramic powder comprise: high melting point (>3000 ℃), high hardness (>30GPa), high chemical stability, high thermal conductivity (120W/mK), high modulus (>570GPa) and excellent electrical conductivity. The method is mainly applied to: hard tool material, composite material additive, novel heating element (1800 deg.C), high-temp. inertiaElectrodes (higher than 1200 ℃), high-temperature wear-resistant electrodes, high-temperature corrosion-resistant electrodes, high-strength lead frame materials for large-scale integrated circuits and the like. But high purity TiB₂The high price of raw materials limits the large-scale development and application of such materials. The traditional synthesis process of titanium diboride ceramic powder comprises the following steps: placing a mixture of titanium or titanium dioxide, boron oxide or boron carbide and carbon in a vacuum graphite tube furnace, and then heating to about 1800 ℃ for carbonization and reduction, wherein the reduction time is generally 1-12 hours. The main disadvantages of this method are: the production device is complex, the reaction temperature is high, the time is long, the energy consumption is huge, and the obtained titanium diboride has large crystal grains, low boron content and poor product purity. Chinese patent CN105533A reports a carbon thermal reduction synthesis method of titanium diboride ceramic powder based on activated carbon as a reducing agent, ammonium pentaborate as a boron source and titanium dioxide as a titanium source, wherein the method needs to be kept at 1450-1700 ℃ for more than 0.5 h, the reaction time is long and the product granularity is large (about 10 mu m).

The self-propagating high-temperature synthesis technology (SHS technology for short) is a new material processing technology which utilizes the heat released by chemical reaction to make the combustion reaction proceed spontaneously so as to obtain combustion products with specified components and structures. Compared with many traditional material preparation technologies, the SHS technology has the following advantages: the process is simple and the process period is short; the energy consumption is low, and the energy-saving effect is obvious; the purity of the synthesized product is high; because the synthesis process experiences a great temperature gradient, a synthetic product with high sintering activity can be obtained. Titanium diboride ceramic powder is one of the materials synthesized earlier by SHS technology, and Z.A. Munir reported an element synthesis method of titanium diboride powder in 1988, which is prepared by using high-purity boron powder and titanium powder or titanium hydride powder as raw materials. The powder synthesized by the process has high purity, but the powder has larger particle size and part of the powder forms hard aggregates; in addition, the adopted raw materials are simple elements, so the manufacturing cost is high, and the industrial production cannot be realized.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the defects in the prior art, a preparation method for preparing titanium diboride ceramic micropowder by using a self-propagating high-temperature reduction synthesis method based on oxide raw materials is provided.

The technical scheme adopted by the invention for solving the technical problems is as follows: adding TiO into the mixture₂、B₂O₃Mixing withMg powder, molding, placing in a self-propagating high-temperature synthesizer (national utility model: ZL93216816.7) under the protection of argon gas at normal temperature and pressure, igniting and burning; crushing and acid-washing the combustion product to obtain high-purity TiB₂And (3) ceramic micro powder.

TiO₂、B₂O₃The powder and metal Mg powder are main reaction materials according to the reaction formula With the formation of a base component of TiB₂And MgO, Q being the reaction exotherm. Because in the above reaction system, TiO₂、B₂O₃The exothermic quantity of the reduction reaction with the metal Mg is far less than that of the synthesis of Ti and B elements, the combustion temperature is lower than 2200 ℃, and the reaction time is finished within a plurality of minutes (generally 1-2 minutes), so that the formed product has fine grains, does not agglomerate and is easy to break.

The specific implementation process of the invention is described in detail as follows:

1. adding TiO into the mixture₂、B₂O₃Mixing with Mg powder, molding, placing in a self-propagating high-temperature synthesizer (national utility model: ZL93216816.7) under the protection of argon gas at normal temperature and pressure, igniting and burning to obtain combustion product.

Wherein the TiO is₂The particle size of the powder is less than 80 mu m, B₂O₃The particle size of the powder should be less than 120 μm, and the particle size of the Mg powder should be less than 200 μm.

TiO for self-spreading high-temp. reduction synthesis₂、B₂O₃The Mg powder comprises the following raw materials in percentage by weight: TiO 2₂27-29 wt%, B₂O₃26-28 wt% of Mg and 43-47 wt% of Mg.

2.TiB₂The purification and separation of the ceramic micro powder can be realized according to the following processes: crushing the combustion products by a ball mill and sieving to obtainPowder with particle size less than 0.5 mm; and (3) placing the powder into a reaction kettle, pickling the powder in hydrochloric acid or sulfuric acid with the concentration of 0.5-2.0 mol/l at the temperature of 20-80 ℃ for 1-10 hours, and filtering and drying the obtained product to obtain the high-purity titanium diboride ceramic micro powder.

Synthesizing high-purity TiB by combining self-propagating high-temperature reduction synthesis (SHRS) technology with chemical purification₂The ceramic micro powder comprises the following components: 78-69 wt% of Ti67, 32-32 wt% of B29, less than or equal to 0.75 wt% of O, less than or equal to 0.1 wt% of N, less than or equal to 0.15 wt% of Mg, and 5 mu m of average grain diameter.

The invention has the advantage that compared with the traditional carbon thermal reduction of TiB₂The ceramic powder has high purity, fine crystal grains, simple process and low energy consumption and time consumption; simultaneously synthesizing TiB with SHS simple substance₂Compared with the ceramic powder, the manufacturing cost is about 20 percent, and the grain size is 1/10-1/4 percent.

Detailed description of the preferred embodiments

Example 1: 27 g TiO₂Powder (less than or equal to 80 mu m) and 26 g of B₂O₃Powder (less than or equal to 120 mu m) and 47 g of Mg powder (less than or equal to 200 mu m) are fully mixed. Pressing the mixed sample into a block blank, putting the block blank into a self-propagating high-temperature synthesis reactor, and performing argon synthesis at normal temperature and normal pressureUnder the protection of gas, the surface of the sample is ignited by tungsten filament or electric arc. The combustion wave rapidly spreads, the combustion temperature of the sample is 1800-2000 ℃, and the combustion reaction is completed within 1-2 minutes. After the sample is completely cooled, the sample is placed in a ball mill for ball milling for 2 hours. Putting the obtained powder into a reaction kettle, adding 10 liters of hydrochloric acid with the concentration of 1mol/l, continuously stirring, pickling for 4 hours at the temperature of 50 ℃, filtering and drying. The components of the obtained micro powder are as follows: ti68.2wt%, B30.1wt%, O0.5wt%, N0.1wt%, Mg0.1wt%, and the average particle diameter was 4.7. mu.m.

Example 2: 29 g TiO₂Powder (less than or equal to 80 mu m) and 26 g of B₂O₃Powder (less than or equal to 120 mu m) and 45 g of Mg powder (less than or equal to 200 mu m) are fully mixed. Pressing the mixed sample into a block blank, putting the block blank into a self-propagating high-temperature synthesis reactor, and igniting the surface of the sample by using a tungsten wire or an electric arc under the protection of argon at normal temperature and normal pressure. The combustion wave rapidly spreads whenThe combustion temperature of the sample is 2000-2200 ℃, and the combustion reaction is completed within 1-2 minutes. After the sample is completely cooled, the sample is placed in a ball mill for ball milling for 2 hours. Putting the obtained powder into a reaction kettle, adding 20 liters of sulfuric acid with the concentration of 0.5mol/l, continuously stirring, pickling for 6 hours at the temperature of 50 ℃, filtering and drying. The components of the obtained micro powder are as follows: ti68.8 wt%, B30.35wt%, O0.7wt%, N0.1wt%, and Mg0.05wt%, with an average particle size of 5.8. mu.m.

Example 3: 29 g TiO₂Powder (less than or equal to 80 mu m) and 28 g of B₂O₃Powder (less than or equal to 1200 mu m) and 43 g of Mg powder (less than or equal to 200 mu m) are fully mixed. Pressing the mixed sample into a block blank, putting the block blank into a self-propagating high-temperature synthesis reactor, and igniting the surface of the sample by using a tungsten wire or an electric arc under the protection of argon at normal temperature and normal pressure. The combustion wave rapidly spreads, the combustion temperature of the sample is 1700-1900 ℃, and the combustion reaction is completed within 1-2 minutes. After the sample is completely cooled, the sample is placed in a ball mill for ball milling for 2 hours. Putting the obtained powder into a reaction kettle, adding 10 liters of hydrochloric acid with the concentration of 1mol/l, continuously stirring, pickling for 4 hours at the temperature of 50 ℃, filtering and drying. The components of the obtained micro powder are as follows: ti67.87wt%, B31.3wt%, O0.6 wt%, N0.1wt%, Mg0.13wt%, and an average particle diameter of 4.1 μm.

Claims

1. The method for preparing high-purity titanium diboride ceramic micropowder by using self-propagating high-temperature reduction synthesis method is characterized by that TiO is added₂、B₂O₃Uniformly mixing Mg powder, carrying out compression molding, putting the mixture in a self-propagating high-temperature synthesis device under the protection of argon at normal temperature and normal pressure, and igniting and burning the mixture to obtain a product mixture;

wherein the TiO is₂The particle size of the powder is less than 80 mu m, B₂O₃The particle size of the powder is less than 120 mu m, and the particle size of the Mg powder is less than 200 mu m;

crushing the product mixture, pickling in hydrochloric acid or sulfuric acid with the concentration of 0.5-2.0 mol/l at the temperature of 20-80 ℃ for 1-10 hours, and filtering and drying the obtained product to obtain high-purity titanium diboride ceramic micropowder;

the micro powder comprises the following components: 78-69 wt% of Ti67, 32-32 wt% of B29, less than or equal to 0.75 wt% of O, less than or equal to 0.1 wt% of N, less than or equal to 0.15 wt% of Mg, and 5 mu m of average grain diameter.